You can barely tighten the adjustable instep closure; 1/2" would be generous. Since I have a very flat instep I need the adjustment,but this is more like a decoration because the amount you can adjust is so minimal. Also, I found the back strap that goes around the heel to be uncomfortable regardless of adjustment. Might just be my foot, but if I kept the shoe I would have to put moleskin on the strap to prevent rubbing my skin raw. Wish it had worked out, it's a cute sandal.